ABSTRACT
Urticaria is characterized by the appearance of transient wheals on skin in any part of the body. The wheals are uncircumscribed, slightly elevated, erythematous, usually pruritic edematous areas in upper dermal tissue. Angioedema is similarly a transient erythematous edema, but involving deeper cutaneous and subcutaneous tissues and usually larger areas. Urticaria and angioedema have many causes and associations. Eosinophils are frequently observed in the otherwise nonspecific inflammatory infiltrate of urticaria. Skin biopsy specimens from chronic urticaria have shown extracellular eosinophil granule protein localization in 43–60% of lesions. The extracellular protein was prominent and deposition occurred in three patterns: around small blood vessel walls, as granules dispersed in the dermis, and as focal or diffuse immunofluorescence of connective tissue fibers. Episodic angioedema associated with eosinophilia, first described in 1984, is characterized by recurrent angioedema, urticaria, fever, and elevated levels of IgM. The wheal-and-flare cutaneous reaction is characteristic of type I, immunoglobulin E-mediated hypersensitivity.
